365 lines
12 KiB
Diff
365 lines
12 KiB
Diff
commit de1a9197af7f67a89f929dcadb8ceca8c3846b1c
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Fri Oct 30 11:57:59 2020 +0100
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elf: Unify old and new format cache handling code in ld.so
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struct file_entry_new starts with the fields of struct file_entry,
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so the code can be shared if the size computation is made dynamic.
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Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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diff --git a/elf/dl-cache.c b/elf/dl-cache.c
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index ef37ca18fa9fb6e0..366a051dfcd26132 100644
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--- a/elf/dl-cache.c
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+++ b/elf/dl-cache.c
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@@ -35,103 +35,141 @@ static struct cache_file *cache;
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static struct cache_file_new *cache_new;
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static size_t cachesize;
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-/* 1 if cache_data + PTR points into the cache. */
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-#define _dl_cache_verify_ptr(ptr) (ptr < cache_data_size)
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-
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-#define SEARCH_CACHE(cache) \
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-/* We use binary search since the table is sorted in the cache file. \
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- The first matching entry in the table is returned. \
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- It is important to use the same algorithm as used while generating \
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- the cache file. */ \
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-do \
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- { \
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- left = 0; \
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- right = cache->nlibs - 1; \
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- \
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- while (left <= right) \
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- { \
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- __typeof__ (cache->libs[0].key) key; \
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- \
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- middle = (left + right) / 2; \
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- \
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- key = cache->libs[middle].key; \
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- \
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- /* Make sure string table indices are not bogus before using \
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- them. */ \
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- if (! _dl_cache_verify_ptr (key)) \
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- { \
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- cmpres = 1; \
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- break; \
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- } \
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- \
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- /* Actually compare the entry with the key. */ \
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- cmpres = _dl_cache_libcmp (name, cache_data + key); \
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- if (__glibc_unlikely (cmpres == 0)) \
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- { \
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- /* Found it. LEFT now marks the last entry for which we \
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- know the name is correct. */ \
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- left = middle; \
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- \
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- /* There might be entries with this name before the one we \
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- found. So we have to find the beginning. */ \
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- while (middle > 0) \
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- { \
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- __typeof__ (cache->libs[0].key) key; \
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- \
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- key = cache->libs[middle - 1].key; \
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- /* Make sure string table indices are not bogus before \
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- using them. */ \
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- if (! _dl_cache_verify_ptr (key) \
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- /* Actually compare the entry. */ \
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- || _dl_cache_libcmp (name, cache_data + key) != 0) \
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- break; \
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- --middle; \
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- } \
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- \
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- do \
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- { \
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- int flags; \
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- __typeof__ (cache->libs[0]) *lib = &cache->libs[middle]; \
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- \
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- /* Only perform the name test if necessary. */ \
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- if (middle > left \
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- /* We haven't seen this string so far. Test whether the \
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- index is ok and whether the name matches. Otherwise \
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- we are done. */ \
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- && (! _dl_cache_verify_ptr (lib->key) \
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- || (_dl_cache_libcmp (name, cache_data + lib->key) \
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- != 0))) \
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- break; \
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- \
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- flags = lib->flags; \
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- if (_dl_cache_check_flags (flags) \
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- && _dl_cache_verify_ptr (lib->value)) \
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- { \
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- if (best == NULL || flags == GLRO(dl_correct_cache_id)) \
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- { \
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- HWCAP_CHECK; \
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- best = cache_data + lib->value; \
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- \
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- if (flags == GLRO(dl_correct_cache_id)) \
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- /* We've found an exact match for the shared \
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- object and no general `ELF' release. Stop \
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- searching. */ \
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- break; \
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- } \
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- } \
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- } \
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- while (++middle <= right); \
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- break; \
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- } \
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- \
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- if (cmpres < 0) \
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- left = middle + 1; \
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- else \
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- right = middle - 1; \
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- } \
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- } \
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-while (0)
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+/* True if PTR is a valid string table index. */
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+static inline bool
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+_dl_cache_verify_ptr (uint32_t ptr, size_t string_table_size)
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+{
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+ return ptr < string_table_size;
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+}
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+
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+/* Compute the address of the element INDEX of the array at LIBS.
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+ Conceptually, this is &LIBS[INDEX], but use ENTRY_SIZE for the size
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+ of *LIBS. */
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+static inline const struct file_entry *
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+_dl_cache_file_entry (const struct file_entry *libs, size_t entry_size,
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+ size_t index)
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+{
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+ return (const void *) libs + index * entry_size;
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+}
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+
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+/* We use binary search since the table is sorted in the cache file.
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+ The first matching entry in the table is returned. It is important
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+ to use the same algorithm as used while generating the cache file.
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+ STRING_TABLE_SIZE indicates the maximum offset in STRING_TABLE at
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+ which data is mapped; it is not exact. */
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+static const char *
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+search_cache (const char *string_table, uint32_t string_table_size,
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+ struct file_entry *libs, uint32_t nlibs, uint32_t entry_size,
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+ const char *name)
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+{
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+ /* Used by the HWCAP check in the struct file_entry_new case. */
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+ uint64_t platform = _dl_string_platform (GLRO (dl_platform));
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+ if (platform != (uint64_t) -1)
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+ platform = 1ULL << platform;
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+ uint64_t hwcap_mask = GET_HWCAP_MASK ();
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+#define _DL_HWCAP_TLS_MASK (1LL << 63)
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+ uint64_t hwcap_exclude = ~((GLRO (dl_hwcap) & hwcap_mask)
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+ | _DL_HWCAP_PLATFORM | _DL_HWCAP_TLS_MASK);
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+
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+ int left = 0;
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+ int right = nlibs - 1;
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+ const char *best = NULL;
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+
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+ while (left <= right)
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+ {
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+ int middle = (left + right) / 2;
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+ uint32_t key = _dl_cache_file_entry (libs, entry_size, middle)->key;
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+
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+ /* Make sure string table indices are not bogus before using
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+ them. */
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+ if (!_dl_cache_verify_ptr (key, string_table_size))
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+ return NULL;
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+
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+ /* Actually compare the entry with the key. */
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+ int cmpres = _dl_cache_libcmp (name, string_table + key);
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+ if (__glibc_unlikely (cmpres == 0))
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+ {
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+ /* Found it. LEFT now marks the last entry for which we
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+ know the name is correct. */
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+ left = middle;
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+
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+ /* There might be entries with this name before the one we
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+ found. So we have to find the beginning. */
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+ while (middle > 0)
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+ {
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+ key = _dl_cache_file_entry (libs, entry_size, middle - 1)->key;
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+ /* Make sure string table indices are not bogus before
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+ using them. */
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+ if (!_dl_cache_verify_ptr (key, string_table_size)
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+ /* Actually compare the entry. */
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+ || _dl_cache_libcmp (name, string_table + key) != 0)
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+ break;
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+ --middle;
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+ }
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+
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+ do
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+ {
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+ int flags;
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+ const struct file_entry *lib
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+ = _dl_cache_file_entry (libs, entry_size, middle);
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+
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+ /* Only perform the name test if necessary. */
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+ if (middle > left
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+ /* We haven't seen this string so far. Test whether the
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+ index is ok and whether the name matches. Otherwise
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+ we are done. */
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+ && (! _dl_cache_verify_ptr (lib->key, string_table_size)
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+ || (_dl_cache_libcmp (name, string_table + lib->key)
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+ != 0)))
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+ break;
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+
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+ flags = lib->flags;
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+ if (_dl_cache_check_flags (flags)
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+ && _dl_cache_verify_ptr (lib->value, string_table_size))
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+ {
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+ if (best == NULL || flags == GLRO (dl_correct_cache_id))
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+ {
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+ if (entry_size >= sizeof (struct file_entry_new))
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+ {
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+ /* The entry is large enough to include
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+ HWCAP data. Check it. */
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+ struct file_entry_new *libnew
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+ = (struct file_entry_new *) lib;
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+
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+ if (libnew->hwcap & hwcap_exclude)
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+ continue;
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+ if (GLRO (dl_osversion)
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+ && libnew->osversion > GLRO (dl_osversion))
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+ continue;
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+ if (_DL_PLATFORMS_COUNT
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+ && (libnew->hwcap & _DL_HWCAP_PLATFORM) != 0
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+ && ((libnew->hwcap & _DL_HWCAP_PLATFORM)
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+ != platform))
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+ continue;
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+ }
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+
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+ best = string_table + lib->value;
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+
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+ if (flags == GLRO (dl_correct_cache_id))
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+ /* We've found an exact match for the shared
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+ object and no general `ELF' release. Stop
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+ searching. */
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+ break;
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+ }
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+ }
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+ }
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+ while (++middle <= right);
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+ break;
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+ }
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+ if (cmpres < 0)
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+ left = middle + 1;
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+ else
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+ right = middle - 1;
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+ }
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+
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+ return best;
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+}
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int
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_dl_cache_libcmp (const char *p1, const char *p2)
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@@ -182,12 +220,6 @@ _dl_cache_libcmp (const char *p1, const char *p2)
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char *
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_dl_load_cache_lookup (const char *name)
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{
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- int left, right, middle;
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- int cmpres;
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- const char *cache_data;
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- uint32_t cache_data_size;
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- const char *best;
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-
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/* Print a message if the loading of libs is traced. */
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if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS))
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_dl_debug_printf (" search cache=%s\n", LD_SO_CACHE);
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@@ -247,51 +279,22 @@ _dl_load_cache_lookup (const char *name)
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/* Previously looked for the cache file and didn't find it. */
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return NULL;
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- best = NULL;
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-
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+ const char *best;
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if (cache_new != (void *) -1)
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{
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- uint64_t platform;
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-
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- /* This is where the strings start. */
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- cache_data = (const char *) cache_new;
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-
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- /* Now we can compute how large the string table is. */
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- cache_data_size = (const char *) cache + cachesize - cache_data;
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-
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- platform = _dl_string_platform (GLRO(dl_platform));
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- if (platform != (uint64_t) -1)
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- platform = 1ULL << platform;
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-
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- uint64_t hwcap_mask = GET_HWCAP_MASK();
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-
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-#define _DL_HWCAP_TLS_MASK (1LL << 63)
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- uint64_t hwcap_exclude = ~((GLRO(dl_hwcap) & hwcap_mask)
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- | _DL_HWCAP_PLATFORM | _DL_HWCAP_TLS_MASK);
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-
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- /* Only accept hwcap if it's for the right platform. */
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-#define HWCAP_CHECK \
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- if (lib->hwcap & hwcap_exclude) \
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- continue; \
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- if (GLRO(dl_osversion) && lib->osversion > GLRO(dl_osversion)) \
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- continue; \
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- if (_DL_PLATFORMS_COUNT \
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- && (lib->hwcap & _DL_HWCAP_PLATFORM) != 0 \
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- && (lib->hwcap & _DL_HWCAP_PLATFORM) != platform) \
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- continue
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- SEARCH_CACHE (cache_new);
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+ const char *string_table = (const char *) cache_new;
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+ best = search_cache (string_table, cachesize,
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+ &cache_new->libs[0].entry, cache_new->nlibs,
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+ sizeof (cache_new->libs[0]), name);
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}
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else
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{
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- /* This is where the strings start. */
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- cache_data = (const char *) &cache->libs[cache->nlibs];
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-
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- /* Now we can compute how large the string table is. */
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- cache_data_size = (const char *) cache + cachesize - cache_data;
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-
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-#undef HWCAP_CHECK
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-#define HWCAP_CHECK do {} while (0)
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- SEARCH_CACHE (cache);
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+ const char *string_table = (const char *) &cache->libs[cache->nlibs];
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+ uint32_t string_table_size
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+ = (const char *) cache + cachesize - string_table;
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+ best = search_cache (string_table, string_table_size,
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+ &cache->libs[0], cache->nlibs,
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+ sizeof (cache->libs[0]), name);
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}
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/* Print our result if wanted. */
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diff --git a/sysdeps/generic/dl-cache.h b/sysdeps/generic/dl-cache.h
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index cf43f1cf3b441bc7..3c5730dfe42c7c88 100644
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--- a/sysdeps/generic/dl-cache.h
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+++ b/sysdeps/generic/dl-cache.h
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@@ -59,8 +59,8 @@
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*/
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struct file_entry
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{
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- int flags; /* This is 1 for an ELF library. */
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- unsigned int key, value; /* String table indices. */
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+ int32_t flags; /* This is 1 for an ELF library. */
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+ uint32_t key, value; /* String table indices. */
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};
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struct cache_file
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@@ -77,8 +77,17 @@ struct cache_file
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struct file_entry_new
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{
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- int32_t flags; /* This is 1 for an ELF library. */
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- uint32_t key, value; /* String table indices. */
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+ union
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+ {
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+ /* Fields shared with struct file_entry. */
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+ struct file_entry entry;
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+ /* Also expose these fields directly. */
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+ struct
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+ {
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+ int32_t flags; /* This is 1 for an ELF library. */
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+ uint32_t key, value; /* String table indices. */
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+ };
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+ };
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uint32_t osversion; /* Required OS version. */
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uint64_t hwcap; /* Hwcap entry. */
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};
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